Power over Ethernet (PoE) is a known technology that allows network cables to carry electrical power. Thus, PoE-enabled devices can receive power as well as data through the twisted pairs of an Ethernet cable. PoE can provide many advantages for installations, including reducing time and expense of installing electrical power cables. PoE-enabled devices do not require mains AC electrical outlets to operate and PoE systems can also protect equipment from overload.
The 802.3 PoE standard defines two types of PoE implementation:                Mode A—power is sent together with the data on twisted pairs 1/2 & 3/6 of the Ethernet cable        Mode B—data is sent on pairs 1/2 & 3/6, and power is sent on pairs 4/5 and 7/8 of the Ethernet cable as pairs 4/5 and 7/8 are unused in Fast Ethernet networks. In the case of Gigabit and 10G Ethernet all 4 pairs are used for both data and power transmission so an alternative mode implements a simplex, or ‘phantom’ power method for delivering power to the end device and power is carried on the same conductors as data.        
CAT-5 cabling for standard 10 BaseT and 100 Base-TX Ethernet uses two data/signal pairs connected to pins 1 and 2 and pins 3 and 6 on RJ-45 connectors. Power sourcing equipment injects power onto these pins via the centre tap of internal signal coupling transformers. In the powered device the power is derived from these lines using a reverse technique. There are powered devices that can operate in Gigabit Ethernet networks. These use transformers that enable transmission of power along with the data (as in mode A of 802.3). An alternative mode B carries power over spare wire pairs in the cable. The power sourcing equipment applies positive voltage to pins 4 and 5. Negative voltage is applied to pins 7 and 8.
Conventionally, one device is powered using one PoE cable. Also, the amount of power that can be transferred using PoE is limited (typically around 13-25 W). There is therefore a strong drive in the electronics industry to develop ways of transferring greater power using PoE in order to accommodate high-energy devices, and therefore broaden the types of devices that can be used with PoE, which have typically been restricted to IP Phones and fixed IP CCTV cameras. However, the use of a standard Ethernet-cabling infrastructure for a single port delivering greater than 100 W is not safe under the current US National Electric Code standard and increasing loads could result in overheating causing melted wires and potential fires.
It is an aim of example embodiments of the present invention to address at least one disadvantage of the prior art, whether identified herein or otherwise.